appcoef - approximation coefficient extraction for one dimensional multiple stride fast discrete wavelet decompostion

Calling Sequence

ac=appcoef(c,l,wavename,level,[extension_method])

Parameters

• c : Coefficient Bunch Vector
• l : Coefficient Length Array
• wavename : wavelet name
  • 'haar': haar wavelet
  • 'db1': daubechies 1 wavelet, same with haar
  • 'db2': daubechies 2 wavelet
  • 'db3': daubechies 3 wavelet
  • 'db4': daubechies 4 wavelet
  • 'db5': daubechies 5 wavelet
  • 'db6': daubechies 6 wavelet
  • 'db7': daubechies 7 wavelet
  • 'db8': daubechies 8 wavelet
  • 'db9': daubechies 9 wavelet
  • 'db10': daubechies 10 wavelet
• level : Decompostion Level of the coefficient you want
• extension_method : Signal Extension Method, default is 'symh'
  • 'zpd': zero padding method
  • 'ppd': period extension method
  • 'asymh': half asymmetric extension method
  • 'asymw': whold asymmetric extension method
  • 'symh': half symmetric extension method
  • 'symw': whole symmetric extension method
  • 'sp0': border value constant extension method
  • 'sp1': border value linear extension method
• ac : Approximation Coefficient

Description

This function extracts approximation coefficent from coefficent bunch vector. Almost all level approximation coefficients are obtained from inverse wavelet transform. So the wavelet name and extension method should be presented, consistently with those of the decomposition procedure. Only the highest decomposed approximation coefficent does not need inverse transform.

Examples

-->sig=rand(1,64);
-->[c,l]=wavedec(sig,3,'db2','symh');
-->a1=appcoef(c,l,'db2',1,'symh');
-->length(a1)
 ans  =
 
    33.     
-->a2=appcoef(c,l,'db2',2,'symh');
 -->length(a2)
 ans  =
 
    18.    


  

See Also

detcoef ,   wrcoef ,   appcoef2 ,   detcoef2 ,   wrcoef2